Editor's Note: Some of the articles described below are not yet available at the PNAS site, but they are scheduled to be posted some time this week.
In a study slated to appear this week in the Proceedings of the National Academy of Sciences, researchers from Canada and Saudi Arabia used genome sequencing to get a peek at population patterns and selective pressures in the honeybee, Apis mellifera. The team sequenced 39 A. mellifera bees sampled from lineages in Africa, Asia, and Europe, along with a lone representative from the A. cerana species. By searching for signs of positive selection in these sequences, the investigators pinpointed genes and regulatory sequences that have undergone adaptations in bees from different castes. For instance, their results suggest fitness effects are typically more pronounced when changes occur in highly expressed worker bee genes relative to those expressed highly in queen bees.
A team from Sweden, Germany, and Russia reports on a statistical scheme for distinguishing ancient DNA from modern contaminants. By applying this method to DNA from a contaminated Neanderthal bone found in a cave in Siberia, for instance, the researchers managed to dial down the signal stemming from modern human DNA and develop a high-quality mitochondrial sequence for the Neanderthal. That sequence "is more closely related to the variation of Western Neanderthals than what was discernible from previous analyses," the study's authors note, arguing that their new approach "opens up the potential for genomic analyses of contaminated fossil material."
Bladder cancers can be grouped into at least two sub-types using information on their nucleotide and chromosome-level mutations, according to another PNAS study. A Roswell Cancer Institute-led team performed whole-genome sequencing on matched tumor and normal samples from five individuals with a form of bladder cancer called muscle-invasive transitional cell carcinoma of the urinary bladder. The researchers found that one group of p53 mutation-containing tumors was prone to a slew of structural variations, single nucleotide mutations, and dramatic chromosomal mutations, while the group of tumors lacking p53 mutations tended to have more subtle mutational profiles.